Amplifying arrangement



A. J. MADDOCK AMPLIFYING ARRANGEMENT Dec. 30, 1947.

Filed June 1.2, 1945 cks a yV W M, 7 7 M,

Patented Dec. 30, 1947 f'Alan Julian ll'laddock,` London,

England, assignon Vby mesne assignments, to International StandardElectric `(lorporation, corporation of Delaware New York, N. Y., -a

Application June 1 2, 11943,Serigl No.1'490,'5851 l In Great BritainJuly 3, 1942 Claims.

'The -`present invention vrelates Ito amplifying `arrangeiner-1t's `andvparticularl'y` to 'amplifying system feeding two or more loads, suchfas antennae, with currents having diierent relative phases.

With directive antenna systems in which two or more antennae are to befed with current of different relative Aphases :it is usually essentialthat the magnitudes and phases of the currents should not vary withrespect -to one another due to variations in amplifier characteristics.These conditions are particularly important, for example, in systemsused for guidance of aircraft, ships, etc., where two lover-lapping eldstrength patterns are used Jvcapable ofheing radiated :in seme4rhyitmn'ic manner sb that on each side of the line Yjoining theintersection 'ofthe two patterns and the centre fof theV antenna systema different and `distinctive .signal iis radiated whilst -on theintersecting line a continuous signal is obtained; this is produced forexample by radiating one pattern for the period of Va dash landthe/other pattern 'for the period lof a fdot, the `two following eachother regularly.

Under such circumstances -i-t yispre'ferable that all antennae 'should"be #energised by the same amplier system to -bbviate any ldifference ofphase or magnitudearising between the antennae which might occur 'ifseparate jam'p'liiiers'are used. In many instances it is 'possible to'do this but for som-e applications heretoforefit hasbee'n foundnecessary to use separate 'amplifiers 4with the abovementionedjdiculties arising thereby.v It is the purpose -of-this"invention to provide a systern whereby the antennae are energised bythe same amplifier thus `Aleading te 'elimination of effects arisingfrom variations of magnification in the valves of the -ampaflenvariations of grid driving volts, variations Iol high tension anodesupply, etc. The scheme will be "considered with particular reference-to an approach system having three driven or lerie'nglised antennae,the currents in which diner in v'phase `and magnitude and it will fbeshown herinaiter how characteristic changesY ofthe "adiated pattern maybe effected in simple manner whilst still retaining all the aboveadvantages.

Accrding to 'the invention an electronic discharge device-amplifyingsystem arranged to feed power inte tw-0 n die loads fis charaeterisei inthis that it "coin 'es two amplifying arrangemerits fed'from the sainevsource fin push-pull and parallel linode'sA with 'any desired amount'of phase dinerene'e vbetweein 'the Adriving voltages for the two'modes'. vand thatme lead circuits are so coupled to the output circuitsnf 1the two ampliplifier circuits.

Referring to Fig. '1, A and rB are thermionic 'amplifying valves `eachhaving grid input and anode output circuits resonant yto the frequencyof operation, the `circuits 'of the valves being `dis posed relative toea'ch other so as to have negligible reaction between each other. '(Thesources of supply for cathode and grid are not shown as not beingrelevant to the 'invention and thesemay be arranged in any knownmanner.) 'The three valves X, Y and Z have their grid inputcircuitsconnected in parallel and excited from the common source of radiofrequency as shown. The valve Z has a phase 'shifting network yKinserted in its fg'rid circuit so that the phase of the voltage appliedto its `grid relative to that applied 'to X or Ymay beset to la-fdesiredvalue.

Onlyone of 'thevalv'es X or Y is permitted to amplify at vvatiine, thegrids o'f these valves being connected to sources of large negativevalue via 'a keying system connected at GKS, and any sultable keyingsystem may be employed, but a .particularly 'suitable arrangement isdisclosed in `my British Patent Number 558.224 of March 2l). 1944, sothat keying may be eiie'cte'd in complementary fashion withinstantaneous 'changeover between the two values. 'I-'hus when valve Xis amplifying say for the period of a da'Sh, Y is blocked and then Yamplies for the period of a dot and X is blocked and so on. A'push-'pullcircuit is connected Yto the outputs of valves X and'Y and lconsists ofthe coils L1 and condensers`C1, the centre point of which latter isreturned to the valve cathodes and the coi-ls L1 are so 'connected as tobe series aiding for the push-pull voltage, thus driving the valves -Aand B in push-pull through the intermediary v'of the coupling-existingbetween coils L1 and La. The 'anode utuned circuit LiCi is excited fromeither side alternately at the points :t and y by the valves X and Y,respectively, by means of the complementary keying arrangements referredto and connected at CKS, and 'thus a phase change of 180 may vbeobtained in the push-pull driving volts applied tothe grids of vA Vand Bas desired yby the keying rhythm. Y

At the same time :as A and B are driven in push-pull mode they are alsodriven in the parallel mode at the same frequency by the valve Z havingoutput circuit LzCz, the coils Lz being so connected and coupled tocoils L3 that the grids of A and B are driven in parallel. The phasedifference between the parallel and pushpull voltages is The valves Aand B will thus have a resultant voltage equal to the vector sum of thepush-pull and parallel voltages applied to their grids and will amplifysame and develop corresponding voltages in the output circuitsfCiA, L1Aand Cna, Lne. By connecting coils Ls-tuned by con-V densers Cs-in suchsense as to be series aiding for the push-pull voltages in Lui and L43only such voltage and hence such power will bedelivered to antennae Pand Q whilst coils La (tuned by condenser Ce) are connected in suchsense as to be series aiding for the parallel voltages in L4A and Ln; sothat only such voltage, and hence such power, is delivered to antenna C.With the arrangement as shown, the currents fed to the two antennae Pand Q will differ by 180 and that fed to C will differ from that fed toone antenna of P or Q by the amount of phase shift introduced 'at K andby 180 minus this shift from the other of P or Q; as X and Y are keyedthe phases of the two antennae P and Q will be changed by 180 as alreadydescribed.

Thus with this arrangement the power fed to all antennae is supplied bythe same amplifier system (viz. A and B) so that any variation of anodesupply or variations in valves affect all antennae equally and hence donot cause relative changes in the radiated eld patterns but only changesof magnitude which are unimportant.

The amplifiers X, Y, Z, A and B may be operated under any condition butin a preferred arrangement they would all operate as Class C ampliers(it will be shown Vbelow that Class C operation is possible) since thenvariations of grid drive will not affect the output and thus even ifvalves X and Y did induce different voltages on the grids of A and B theoutput in the two cases would still be the same. For the same reason anyvariation in Z would not cause changes in the relative outputs.Preferably, also valves X, Y and Z would have the same source of anodetension suppy so that variations are still further reduced. If theValves are operating under Class A or Class B conditions, the radiofrequency input may be modulated if required or with the preferred ClassC working valves A and B may be anode modulated.

Relative phase changes between P, Q and C other than those automaticallyobtained above may be introduced if desired by variation of length ofthe transmission lines feeding the antennae or by the introduction ofphase shifting networks in the feed to said antennae in manner wellknown in the art.

In Fig. 2 in which ordinates represent amplitude and abscissae representelectrical degrees, the push-pull voltages induced in the grid circuitsof A and B are shown at P-P Voltage of A or of B and the parallelvoltage applied to A and B simultaneously is shown at parallel voltageof A and B of amplitude equal to the push-pull voltage and diiering inphase therefrom by 90 and +90 respectively. The resultant voltagesapplied to the grids of A and B are as shown at resultant voltage of Aor B in the heavy lfull and dashed lines respectively andthe anodevoltages in the output circuits L4. Cia, L43 C413 determined by thenetwork Y Vtion, from the output 4 would be correspondingly similar andit can readily be seen that since these voltages were built up byinjecting two voltages in push-pull and parallel and differing in phaseas hereinbefore stated, they may be separated utilising push-pull andparallel circuits after amplicacircuits of valves A and B.

- It is known that if two sine waves of the same vfrequency and anyrelative amplitude and phase are combined the resulting wave is also asine w`ave:"y ifY e sin wt represents one wave and e1 sin (wt-gbl theother where e and e1 are the amplitudes, a the angular frequency, t thetime and p the phase difference between the two waves; then it can beshown that the resultant wave is represented by which, since allfactorsl except wt are constant, is of sine wave form. In the specialcase when e=e1 this reduces to Eu=2e cos .1s/2. sin (wr-qq2) (a) and inthe further special case when =1r/2 (and e=e1), Equation 2 or 3 reduceto MFM/. sin (wt-WM.) (4) In the arrangements of the present inventionthe output voltages of 'valves AV and B must simulate those applied totheir grids so that the resultants may be analysed into their componentsand this may readily be done if A and B work under Class A or Bconditions. In Class C operation, even a distorted input voltage willgive a sine wave voltage in the output so that normally this type ofampliiier is not used to follow variationsv of grid circuit voltage.However, since, as we have shown, the grid input voltage in thesearrangements is always of sine wave form we may utilise this class ofoperation and so obtain output voltages following the grid voltages.

With the special case considered of a phase shift being introduced at K(Fig. 1) of 90 we are able to feed an antenna system very suitable foruse in guiding or approach systems wherein a centre antenna is fed withcurrent of constant magnitude and two outer antennae are fed withcurrents displaced and '+90 with respect to the centre antenna and theseouter currents can be instantaneously changed in phase by to obtain therequired change of eld pattern. The relative magnitudes of the currentscan be altered by variation of the coupling between L5 and L4 or betweenLa and L4. Y

There is no interaction between the parallel and push-pull circuits whenarranged as described, for the voltage induced in say one parallel coil(L2 top) by the neighbouring push-pull coil (L1 top) will be annulled byan equal voltage induced in the bottom L2 coil due to the way in whichthe coils are connected and similarly interaction in the opposite senseis annulled.

The foregoing description has detailed the case of an antenna system inwhich instantaneous keying is required but it is clear that the systemis equally applicable to systems in which constant radiation is to beemitted and it is readily evident that any number of antennae greaterthan one, may be fed in this manner in which case one of the valves X orY may be omitted. For example for two antennae one is fed by theparallel coils L6 and the other by the push-pull coils L in which casethe condenser C5 need not be split. For three antennae the schemealready described may be employed if two of the antennae are to differin phase by 180 or as mentioned subsequent phasing networks or lines maybe inserted. Four antennae may be similarly driven arranged for examplein pairs, the coils L5 driving one pair and coils Ls another pair. Andso on, variations in the arrangements described being readily apparentto those skilled in the art and coming within the scope of the inventionas defined in the appended claims.

Similar keying arrangements may be provided if desired for the paralleldrive in which case a split driving circuit Vwould be provided for thismode and two valves instead of the one Z with a similar arrangement ofkeying as already described for X and Y. Both the parallel and push-pulldriving keyed circuits may be provided together.

Whilst the phasing network K has been shown in the grid circuit of valveZ it may equally well be inserted in the anode circuit thereof. It is anadded advantage of the scheme that phasing of the antenna currents maybe effected in low power circuits where control is readily possible.

Although reference has been made throughout to the power being deliveredto an antenna system this is not meant to imply a limitation on theinvention since any load may be employed and furthermore the inventionis applicable to arrangements using other frequencies than radiofrequencies.

What is claimed is:

1. An amplifying system employing electron discharge devices and adaptedto feed power into a plurality of load circuits comprising a pair ofvalves having input and output circuits, a source of high frequencyvoltage, means to feed voltages from said source to the input circuitsof said valves in push-pull and parallel modes with predetermined phasedisplacement between the voltages of said modes, a plurality of loadcircuits, means to couple one of said load circuits to the outputcircuits of said valves so as to transfer power in one mode, and meansto couple another load circuit to said output circuits so as to transferpower in said other mode.

2. An amplifying system in accordance with claim 1 in which the feedingmeans for the input circuits of the valves includes a phase adjustmentdevice so that the phase between the two modes may be adjusted.

3. An amplifying system in accordance with claim 1 in which separateamplifying devices are provided to feed the input circuits of the valvesin the different modes.

4. An amplifying system in accordance with claim 1 in which the phasedifference between the push-pull and parallel modes is substantiallyninety electrical degrees.

5. An amplifying system adapted to feed power into a plurality of loadcircuits comprising a first pair of valves having input and outputcircuits, a source of high frequency voltage, a second pair of valveshaving input and output circuits, means to connect said second pair ofvalves in push-pull, means to couple the input circuits of said secondpair of valves inpush-pull arrangement with said first pair of valves, asource of high frequency voltage, means to feed high frequency voltagefrom said source to the input circuits of said rst pair of valves inparallel and with the phase of said voltage displaced a predeterminedamount from that fed to said second pair of valves, a plurality of loadcircuits, means to couple one of said load circuits to said outputcircuits of said first pair of valves so as to transfer power to saidload circuit in the push-pull mode, and means to couple another of saidload circuits to said output circuits for said first pair of valves soas to transfer power to saidload circuit in the parallel mode.

6. An amplifying system in accordance with claim 5 in which means isprovided to adjust the v relative phase of the voltages delivered fromthe claim 5 in which source of high frequency voltage to the inputcircuits of said rst and second pair of valves.

7. An amplifying system in accordance with claim 5 in which a separateamplifier is provided between the source of high frequency voltage andthe means to feed the voltage to the input circuits of the first pair ofvalves in the parallel mode.

8. An amplifying system in accordance with claim 5 in which a separateamplier is provided connected between the source of high frequencyvoltage and the means to feed the input circuits of the first pair ofvalves in the parallel mode, and a phase adjusting device is included inthis feeding circuit.

9. An amplifying system in accordance with means is provided to blockthe valves of the second pair alternately at a predetermined rate.

10. An amplifying system adapted to feed power into a plurality of loadcircuits comprising a rst pair of valves having input and outputcircuits, a second pair of valves having input and output circuits withsaid input circuits connected in push-pull arrangement with the outputcircuits of said first pair of valves, a source of high frequencyvoltage, means to connect said source to the input circuits of saidfirst pair of valves in push-pull arrangement, a fifth valve having aninput and an output circuit, means to connect the input circuit of saidfifth valve to said source of high frequency voltage, means to connectthe input of said fifth valve in parallel with the input circuits ofsaid first pair of valves, means to adjust the phase of the voltagedelivered in parallel to the input circuits of said first pair ofvalves, a plurality of load circuits, means to connect one of said loadcircuits to the output circuits of said rst pair of valves in push-pull,and means to connect another of said load circuits to the outputcircuits of said first pair of valves in parallel.

ALAN JULIAN MADDOCK.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 2,211,942 White Aug. 20, 19402,332,253 Peterson Oct. 19, 1943 1,666,738 Hartley Apr. 17, 19281,773,116 Potter Aug. 19, 1930 1,831,516 Stewart Nov. 10, 1931 1,882,119Chireix Oct. 11, 1932 2,212,230 Goldmann Aug. 20, 1940 1,910,427 DiamondMay 23, 1933 2,203,004 West June 4, 1940

